In a power conversion circuit constituting a power conversion device, such as an inverter device, an uninterruptible power supply device, a power conditioner, various types of power conversion devices for railway vehicles, a machine tool, and an industrial robot, a power semiconductor module to which a power semiconductor element is mounted is used.
As the power semiconductor element which performs switching, a metal oxide semiconductor field effect transistor (MOS-FET) and an insulated gate bipolar transistor (IGBT) made of Si are widely used. In recent years, the power semiconductor element made of a wide bandgap semiconductor, such as SiC and GaN, has been actively researched, developed, and examined for practical use, and also a part of switching elements, such as a Sic-MOSFET, a silicon carbide junction field effect transistor (SiC-JFET), and a gallium nitride high electron mobility transistor (GaN-HEMT), has been already put into practical use.
Above all, in the field of power semiconductor modules, a 2-in-1 module in which in the interior of one module, sets (arms) including a group of switching elements are housed in two series is well known. In the 2-in-1 module, a half-bridge circuit known in the field of power conversion circuits can be composed of one module, and for example, one phase of a three-phase inverter circuit can be made of one module. In the 2-in-1 module, a positive electrode side arm is referred to as upper arm, and a negative electrode side arm as lower arm.
Incidentally, in the field of power electronics in which the power conversion circuit is configured using a power semiconductor module to manufacture the power conversion device, to increase the capacity of power handled in the circuit according to the capacity of the device, employing a plurality of power semiconductor modules connected in parallel is performed (for example, see PTL 1).